How do you find the values of all six trigonometric functions of a right triangle ABC where C is the right angle, given a=20, b=21, c=29?

2 Answers
Feb 23, 2018

cosB=a/c=21/29cosB=ac=2129

sinB=b/c=20/29sinB=bc=2029

tanB=b/a=20/21tanB=ba=2021

cotB=a/b=21/20cotB=ab=2120

secB=c/a=29/21secB=ca=2921

cscB=c/b=29/20cscB=cb=2920

Explanation:

Verification:

20^2=400202=400
21^2=441212=441
20^2+21^2=400+441202+212=400+441
20^2+21^2=841202+212=841
29^2=841292=841
It is confirmed that the triangle is a right angled triangle
a=20a=20
b=21b=21
c=29c=29
C=90^@C=90
Thus with c=29 being considered as hypotenuse
Consider a=21 to form the adjacent side
, and b=20 to form the opposite side
the angle under consideration is B

Now,

cosB=a/c=21/29cosB=ac=2129

sinB=b/c=20/29sinB=bc=2029

tanB=b/a=20/21tanB=ba=2021

cotB=a/b=21/20cotB=ab=2120

secB=c/a=29/21secB=ca=2921

cscB=c/b=29/20cscB=cb=2920

Feb 23, 2018

all trignometric functions of right triangle, AC= hypotenuse=c
BC=a and AC= b are adjacent or opposite sides in accordance to the acute angles, either A or B

Explanation:

if we take angle A as the acute angle,
sinA= a/c=20/29=(opp)/(hyp)sinA=ac=2029=opphyp
cosA=b/c=21/29=(adj)/(hyp)cosA=bc=2129=adjhyp
secA=c/b=29/21=(hyp)/(adj)secA=cb=2921=hypadj
cosecA=c/a=29/20=(hyp)/(opp)cosecA=ca=2920=hypopp
tanA=a/b=20/21=(opp)/(adj)tanA=ab=2021=oppadj
cotA= b/a=21/20=(adj)/(opp)cotA=ba=2120=adjopp
enter image source here
if we take angle B as the acute angle,
sinB= b/c=21/29=(opp)/(hyp)sinB=bc=2129=opphyp
cosB=a/c=20/29=(adj)/(hyp)cosB=ac=2029=adjhyp
secB=c/a=29/20=(hyp)/(adj)secB=ca=2920=hypadj
cosecB=c/b=29/21=(hyp)/(opp)cosecB=cb=2921=hypopp
tanB=b/a=21/20=(opp)/(adj)tanB=ba=2120=oppadj
cotB= a/b=20/21=(adj)/(opp)cotB=ab=2021=adjopp